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Case, Anne, and Deaton, Angus (2020) Deaths of Despair and the Future of Capitalism, Princeton University Press, NJ.
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Multispectral unmanned aerial system remote sensing to detect Dalmatian toadflax in a mixed sagebrush steppe on the South Fork of the Shoshone River
No full textManagement of invasive plant populations is most successful when infestations are identified and managed quickly, but detection of small populations of plants can be difficult. In rangelands of Wyoming, Dalmatian toadflax (Linaria dalmatica) is a competitive invasive forb well-adapted to rocky, dry soil, allowing it to colonize steep slopes and rugged terrain. In the Shoshone National Forest, Dalmatian toadflax populations continue to spread in the nursery slopes of big horn sheep and elk, so Unmanned Aerial Systems (UAS) are being employed for the remote detection of small populations of Dalmatian toadflax. Multispectral profiles of Dalmatian toadflax plants were taken through the growing seasons of 2018 and 2019 to build a spectral signature of the plant. Multispectral imagery of Dalmatian toadflax infested study areas were collected with a UAS, and imagery was classified using a random forest machine learning approach. Spectral signatures of Dalmatian toadflax plants for changes through the growing season, which provides challenges as neighboring species bloom and senesce. Overall, classification results from this study suggest remote detection of Dalmatian toadflax with UAS is possible but must exploit a priori understanding of the phenology of the invaded plant community.
Featured photo by Peter Stevens on Flickr (https://flic.kr/p/cqTyHE)
The role of certain Brauer and Rado results in the nonnegative inverse spectral problems
No full textIt is said that a list of complex numbers is realizable, if it is the spectrum of a nonnegative matrix . It is said that is universally realizable if it is realizable for each possible Jordan canonical form allowed by . This work does not contain new results. As its title says, its goal is to show and emphasize the relevance and importance of certain results, by Brauer and Rado, in the study of nonnegative inverse spectral problems. It is shown that virtually all known results, which give sufficient conditions for to be realizable or universally realizable, can be obtained from results by Brauer and Rado. Moreover, from these results, a realizing matrix may always be constructed
Relaxing the Nonsingularity Assumption for Intervals of Totally Nonnegative Matrices
No full textTotally nonnegative matrices, i.e., matrices having all their minors nonnegative, and matrix intervals with respect to the checkerboard partial order are considered. It is proven that if the two bound matrices of such a matrix interval are totally nonnegative and satisfy certain conditions, then all matrices from this interval are totally nonnegative and satisfy these conditions, too, hereby relaxing the nonsingularity condition in the former paper [M. Adm and J. Garloff. Intervals of totally nonnegative matrices. Linear Algebra Appl., 439:3796--3806, 2013.]
Spectral Properties of Sign Patterns
No full textIn this paper, an infinite family of irreducible sign patterns that are spectrally arbitrary, for which the nilpotent-Jacobian method does not apply, is given. It is demonstrated that it is possible for an irreducible sign pattern to be refined inertially arbitrary and not spectrally arbitrary. It is observed that not every nonzero spectrally arbitrary pattern has a signing which is spectrally arbitrary. It is also shown that every superpattern of the reducible pattern \T_2 \oplus \T_2 is spectrally arbitrary
The least Laplacian eigenvalue of the unbalanced unicyclic signed graphs with pendant vertices
No full textLet be a signed graph and be the Laplacian matrix of , where is the diagonal matrix of vertex degrees of the underlying graph and is the adjacency matrix of . It is well-known that the least Laplacian eigenvalue is positive if and only if is unbalanced. In this paper, the unique signed graph (up to switching equivalence) which minimizes the least Laplacian eigenvalue among unbalanced connected signed unicyclic graphs with vertices and pendant vertices is characterized
On Positive Partial Transpose Matrices
No full textThis paper mainly focuses on the class of block PPT matrices. The relationship between PPT matrices and the norm inequalities is further explored. Some properties of a non-PPT matrix in terms of its eigenvalues are investigated. Moreover, a number of useful sufficient conditions for a matrix to be PPT are provided
Lower bounds for maximal cp-ranks of completely positive matrices and tensors
No full textLet denote the maximal cp-rank attained by completely positive matrices. Only lower and upper bounds for are known, when , but it is known that , and the difference of the current best upper and lower bounds for is of order . In this paper, that gap is reduced to . To achieve this result, a sequence of generalized ranks of a given matrix A has to be introduced. Properties of that sequence and its generating function are investigated. For suitable A, the th term of that sequence is the cp-rank of some completely positive tensor of order . This allows the derivation of asymptotically matching lower and upper bounds for the maximal cp-rank of completely positive tensors of order d>2 as well